Doctor blade multiple-point control

ABSTRACT

A printing-ink receptacle of a printing machine has an elongated outlet and a dispending arrangement is provided which extends along this outlet. The dispensing arrangement includes an elongated flexible doctor blade which extends along the outlet and defines a gap of a predetermined maximum width which is elongated longitudinally of the doctor blade and through which the printing ink is dispensed. An adjusting arrangement is provided for adjusting the width of the gap so as to vary the amount of printing ink dispensed through the same. The adjusting arrangement includes a rotatable eccentric shaft extending along the doctor blade, a plurality of pressure-transmitting bars which engage the doctor blade at respective locations spaced therealong and which are each individually shiftable transversely of the gap to flex the doctor blade and decrease the width of the gap, a drive for rotating the eccentric shaft, and a motion-transmitting arrangement for individually transmitting motion from the shaft to respective ones of the cams to thereby effect shifting of the bar associated with the respective cam.

United States Patent [1 1 Posselt Aug. 12, 1975 DOCTOR BLADE MULTIPLE-POINT CONTROL [75] Inventor:

[73] Assignee: VEB Polygraph Leipzig Kombinat fur Polygraphische Maschinen und Ausrustungen, Leipzig, Germany [22] Filed: Feb. 20, 1974 [21] Appl. No.: 444,246

Heinz Posselt, Leipzig, Germany Primary Examiner-.1. Reed Fisher Attorney, Agent, or Firm-Michael S. Striker 5 7 ABSTRACT A printing-ink receptacle of a printing machine has an elongated outlet and a dispending arrangement is provided which extends along this outlet. The dispensing arrangement includes an elongated flexible doctor blade which extends along the outlet and defines a gap of a predetermined maximum width which is elongated longitudinally of the doctor blade and through which the printing ink is dispensed. An adjusting arrangement is provided for adjusting the width of the gap so as to vary the amount of printing ink dispensed through the same. The adjusting arrangement includes a rotatable eccentric shaft extending along the doctor blade, a plurality of pressure-transmitting bars which engage the doctor blade at respective locations spaced therealong and which are each individually shiftable transversely of the gap to flex the doctor blade and decrease the width of the gap, aldrive for rotating the eccentric shaft, and a motion-transmitting arrangement for individually transmitting motion from the shaft to respective ones of the cams to thereby effect shifting of the bar associated with the respective cam,

8 Claims, 6 Drawing Figures PATENTED AUG 1 2 I975 SPEET SHEET PATENTEU mi 2 I975 PATENTEB AUG 1 2 I975 SHEET DOCTOR BLADE MULTIPLE-POINT CONTROL BACKGROUND OF THE INVENTION The present invention relates generally to a printing machine, and more particularly to a printing machine having a novel arrangement for dispensing of printing ink.

It is well known that in printing machines it is important to be able to vary the amount of printing ink that is transmitted from a printing ink supply to the ductor roller from where the ink is then transmitted to the printing rollers. This is important because different portions of the printing cylinder must be supplied with different amounts of printing ink, depending upon the total surface area within a given portion from which printing ink is to be transmitted to the material being printed. Thus, from some portion of the printing cylinder more ink is to be transmitted to the workpiece than from other portions, and consequently more ink must be applied. Unless this is done, the quality of the final print will not be uniform.

Because of the above mentioned requirements, it is already known in the art to provide adjusting arrangements which vary the width of the gap through which ink is allowed to escape from a printing ink reservoir, to be transferred subsequently to the printing rollers and the printing cylinder. This is conventionally done by providing individual set screws which must be individually adjusted by an operator and which are spaced along the length of the gap through which the printing ink is dispensed, the arrangement being such that by turning the screws in one or the other direction the width of the gap can be slightly varied to thereby increase or decrease the amount of printing ink that can pass through the gap.

As has just been pointed out, in the majority of printing machines the adjustment of these screws must be carried out by an operator who must be present at the printing ink reservoir to individually adjust the screws. Evidently, every time different material must be printed, that is every time a different text, picture or the like is to be printed, the screws must be readjusted. It is hardly necessary to point out that this is time consuming and bothersome. For this reason, various attempts have been made in the prior art to provide arrangements' which permit an adjustment of the width of the gap by remote control, so that the operator need not approach the printing ink receptacle and carry out the adjustment of the screws manually and individually. However, these prior-art arrangements suffer from various drawbacks, including complexity of construction, susceptibility to breakdown, the impossiblity of obtaining a precise adjustment of the gap width, and other disadvantages which have heretofore prevented the use of such arrangements in actual production installations.

SUMMARY OF THE INVENTION Accordingly, it is a general object of the present invention to avoid the disadvantages of the prior art.

More particularly, it is an object of the present invention to provide an arrangement of the type outlined above, in the context of a printing machine, which arrangement is not possessed of the aforementioned disadvantages.

An additional object of the invention is to provide such an arrangement which is simple and uncomplicated in its construction and operation.

Another object of the invention is to provide such an arrangement which permits remote control of its operation, so that the operator can control the device from a central location.

Another object of the invention is to provide such an arrangement in which individual and highly precise adjustments can be made to the width of the gap through which printing ink is dispensed.

In keeping with the above objects, and with others which will become apparent hereafter, one feature of the invention resides, in a printing machine, in a combination which comprises a printing-ink receptacle having an elongated outlet, and dispensing means which includes an elongated flexible doctor blade extending along the outlet and defining a gap of predetermined maximum width which is elongated longitudinally of the doctor blade and through which printing ink is to be dispensed. Adjusting means is provided for adjusting the width of the gap to thereby vary the amount of printing ink that is dispensed through the same. The adjusting means comprises a rotatable eccentric shaft ex tending along the doctor blade, a plurality of pressuretransmitting bars engaging the doctor blade at respective locations which are spaced therealong and each of which is indivudually shiftable transversely of the gap to flex the doctor blade and decrease the width of the gap. A plurality of turnable eccentric cams is provided, each associated with one of the bars for shifting the same transversely of the gap. Drive means rotates the eccentric shaft, and motion-transmitting means individually transmits motion from the shaft to respective ones of the cams so as to effect shifting of the bar which is associated with the same.

With this construction, the aforementioned objects are achieved and in addition damage to various components of the arrangement that could take place as a result of imprecise adjustments, are avoided. Moreover, the gap can be increased or decreased in a very short time, and the increase or decrease can be carried out selectively along the length of the gap, that is the gap can be varied to different extents along its length.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a somewhat diagrammatic fragmentary section taken on line I-I of FIG. 2;

FIG. 2 is a view of FIG. 1, as seen in the direction of the arrow II which is shown in that Figure;

FIG. 3 is a diagrammatic section taken on line IlIIII of FIG. 2, and in addition showing an electric circuit and other associated components;

FIG. 4 is a circuit diagram showing the same portion of FIG. 2 that is illustrated in FIG. 3, and in addition showing the complete circuit of the arrangement, in part as seen in the direction of the arrow IV of FIG. 2',

FIG. Sis a diagrammatic illustration including a circuit diagram, partly sectioned on line VV of FIG. 2; and

FIG. 6 is a detail of FIG. I, in a fragementary perspective view and on an enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the drawing in detail, wherein a single embodiment of the invention is illustrated by way of example in FIGS. 16, it is pointed out that reference numeral 1 identifies a printing-ink receptacle which should be understood to be elongated in direction normal to the plane of FIG. 1, as is evident from FIG. 2 which shows a view of FIG. 1 as seen in the direction of the arrow II. The bottom wall of the receptacle 1 is formed by a flexible doctor blade 2 which also extends longitudinally of the receptacle and which defines with a ductor roller 3 a gap G through which printing ink issues from the receptacle 1. This printing ink leaves the gap G on the peripheral surface of the roller 3 and is transmitted by the same to a transfer roller 4 from whereit is further transferred during the alternate pivoting of the roller 4 as indicated by the curved doubleheaded arrow in FIG. 1, to the printing rollers of which a portion of one is shown in FIG. 1. The amount of printingink that can issue through the gap G depends upon the width of this gap, that is the dimension which is indicated in FIG. 1. The width of the gap G is shown in FIG. 1 to be much larger than it actually is in operation, since the maximum gap width is generally on the order of 1/10 mmjThe doctor blade' 2 is flexible so that if a push is exerted upon it from below, as shown by the elongation of the bars 5, it can be moved closer to the periphery of the roller 3, thereby decreasing the width of the gapG. Furthermore, the doctor blade 2 is also flexible in its longitudinal direction (i.e., in the direction normal to the plane of FIG. 1) so that when the width of the gap G is varied at one location, it is not thereby simultaneously varied at another location that is spaced longitudinally of the doctor blade.

In contradistinction to the conventional adjusting screws that are provided for varying the width of the gap G in most of the prior-art constructions, the present invention utilizes a plurality of pressuretransmitting bars 5 which are spaced from one another lengthwise of the doctor blade 2, as shown in FIG. 2. For purposes of explanation it will be assumed that the doctor blade 2 is subdivided into ten imaginary sections I-X, and that it is desired to be able to vary the width of the gap G in each of these sections individually, that is without effecting the width in the other sections. For this purpose, one of the bars 5 is provided in the region of each of the sections I-X of FIG. 2, and each of the bars 5 is guided in a guide 6 for shifting movement longitudinally of itself. The shifting movement can be imparted to the bars 5 by an eccentric cam 7 associated with each of the bars. The cam 7 is fixedly connected with a gear 9 which is freely turnably mounted on a shaft 10. FIG. 1 shows the arrangement for varying the width of the gap G in one of the zones IX of FIG. 2,

' which are generally identified as color zones 8. The

shaft 10 is surrounded intermediate the gears 9 and cams 7 of the respective zones lVIII by a spacer sleeve 11 to prevent axial displacement of the gears and cams.

Parenthetically, it should be pointed out that it is possible to mount the shaft 10 eccentrically and to provide it with an adjusting mechanism by means of which all of the bars 5 could be simultaneously shifted or brought to a defined zero or inoperative position. This would make it possible to so-operate the construction that the gap G could be completely closed.

Returning to the drawing, it will be seen in FIG. 1 that a leaf spring13 is provided at each of the sections lX, being mounted on a housing 12 of the apparatus and having a portion which engages with the teeth of the gear 9. This prevents turning of the gear 9 and thus of the cam 7, maintaining them both in a once-selected position. For reasons which will be discussed subsequently, the spring 13 extends only over approximately one-third of the axial length of the respective gear 9.

A rod 14 is provided which is formed with a projection 15 that can move into and out of engagement with the teeth of the associated gear 9. The rod 14 is shiftable in a guide 16 that is mounted on the housing 12 and extends through a passage 17 formed in a head portion 18 of another rod 19, one end of which is connected with a spring 23, for instance a helical spring, which is, in turn, fixedly secured to the housing 12. A bifurcated portion 20 is provided on the rod 14, and an eccentric shaft 21 extends through the bifurcated portions 20 of all of the rods 14 at the various sections l-X. The shaft 21 has portions 21a of smallest diameter and portions 21b of largest diameter, or else portions 21b which are eccentrically offset with respect to the axis of the portions 21a. The shaft 21 has opposite axial end portions that are journalled in the housing 12, as shown in FIG. 2, and can be driven via a gear motor 22, as also shown in FIG. 2. Turning of the shaft 21 causes the respective rods 14 to be shifted axially, that is alternately upwardly and downwardly in FIG. 1. In order to bring the projections 15 into and out of engagement with the teeth of the respective gear 9, the rod 19 associated with the respective rod 14 must be operated. Because of the biasing action exerted by the respective spring 23, each of the rods 19 is premanently urged towards the left in FIG. 1, so that each of the associated rods 14 is permanently moved to the full-line position in which its projection 15 is disengaged from the teeth of the associated gear 9. An abutment 24 is provided for this purpose on the end of the rod 19 which is remote from the head portion 18, that is the right-hand end in FIG. 1, and which cooperates with a housing of a solenoid 25 surrounding this right-hand end of the rod 19 so that the latter cannot be pulled by the spring 23 beyond the full-line position shown in FIG. 1.

Solenoids such as the solenoids 25 are well known in the art, and it will be understood that when such a solenoid is energized, it will shift the rod 19 longitudinally of the same. Since the springs 23 urge the rod 19 towards the left in FIG. 1, it is obvious that the solenoid 25 will be employed when energized to shift the same rod towards the right. In so doing, the solenoid 25 will pull the rod 19 towards the right in FIG. 1, and thus displace the rod 14 from the full-line position to the broken-line position in FIG. 1. This requires, of course, that there be sufficient freedom of play in the guide 16 for this purpose When the rod 14 moves to the broken-- line position in FIG. 1, its projection 15 will engage the teeth of the gear 9, and given the fact that the shaft 21 rotates, thus displacing the rod 14 axially of the latter, the gear 9 will be turned by the extent of one tooth. This, of course, causes similar turning of the cam 7 so that the bar 5 is either shifted towards or away from the roller 3, thereby displacing the doctor blade 2 closer to the roller 3 and decreasing the width of the gap G, or permitting to flex further away from the roller 3 and increase the width of the gap G. When subsequently the I solenoid 25 is deenergized, the spring 23 pulls the rod 19 back towards to left again, thereby displacing the rod 14 to the full-line position of FIG. 1, until the abutment 24 engages the housing of the solenoid 25. Since at this time the projection 15 will be out of engagement with the teeth of thegear 9, continued axial displacement of the rod 14 as a result of further rotation of the shaft 21 will not cause any further turning of the gear. Since the leaf spring 13 is always in engagement with the teeth of the gear 9, it will now hold the gear 9 in the position to which it has been turned, and will thus similarly hold the cam 7 in the newly-obtained position.

The shaft 21 is driven by the earlier-mentioned gear motor 22. FIG. 5 shows that for this purpose a cam wheel 26 may be fixedly mounted on one axial end of the shaft 21 to be rotatable with the same. The cam wheel 26 is provided with a recess or depressed land 26' and has associated with it a pair of contacts 27, 27'. The contact 27 is directly displaceable by rotation of the cam wheel 26, and both of the contacts are connected with a switch; 28 so that they can be bridged when the switch is moved to closed position.

When it is desired that the motor 22 should turn the shaft 21 by one revolution, the switch 28 is momentarily closed. As soon as the shaft 21 now turns sufficiently -due to the operation of the motor 22for the projection shown on the contact 27' to move out of the recess 26, the contact 27' will be moved into inductive engagement with the contact 27. As soon as this has taken place, the switch 22 will be opened again since the energizing circuit for the motor 22 will nevertheless remain closed due to the fact that the contacts 27 and 27' are in engagement with one another. This will continue until the projection of the contact 27' reenters into the recess 26 after the cam wheel 26 has performed a complete revolution. It is, of course, possible to maintain the switch 28 in closed position, in which case the motor 22 continues to operate for as long as the switch 28 remains closed and will become deenergized when, after the switch 28 is opened again, the cam wheel 26 has turned sufficiently for the projection of the contact 27' to reenter the recess 26. It will be evident that with this construction, a very rapid adjustment of the gap G in the different color zones 8, that is the sections I-X of FIG. 2, can be carried. For fine adjustments, on the other hand, only a single rotation of the shaft 21 is required at a time.

An eccentric cam 29 is provided, advantageously on the opposite axial end of the shaft 21 from the cam wheel 26, and is provided with a higher land 29b and a lower land 290, each of which extends over approximately 180 of the total circumference of the cam 29. At opposite sides of the cam 29 there are located two pair of contacts, being identified with reference numerals 30 and 30' on the one hand, and 31, 31 on the other hand. This is clearly shown in FIG. 3 from where it will be evident that the land 29b will alternately shift the contact 30' into engagement with the contact 30, and the contact 31 into engagement with the contact 31. A third position is shown in FIG. 3, namely the position in which both of the contacts 30', 31 are out of engagement with their associated contacts 30 and 31, respectively. It should be noted that the land 29b is offset through 90 with respect to the land 21b of the shaft 21, the cam wheel 29 being mounted on a nonexemplary portion of the shaft 21. This means that the position shown in FIG. 3, in which the contacts 13 and 31' do not engage their cooperating contacts 30 and 31, respectively, is reached during each direction reversal in the movement of the respective rod 14. In other words, the switches constituted by the contacts 30, 30 and by the contacts 31, 31', are both open during each reversal in the direction of movement of the rods 14. These two switches control the flow of current to the respective solenoids 25 of which one is associated with each of the sections I-X. FIGS. 3 and 4 show that the two alternately closed switches 30, 30' and'3l, 31 supply current to a control desk 31 which may be located any desired distance from the arrangement and which is shown only in broken lines by way of example. The switch 28 may be provided in this desk 32. This is shown in FIG. 5.

The control desk 32 is also provided with ten zones I-X, corresponding to the zones in FIG. 2. For each of these zones IX, and hencefor each of the solenoids 25, there is provided a so-called alternative switch 33, that is a double-pull double-throw switch having three positions, a neutral position and two operating positions. When the respective switch 33 is in the position shown in FIGS. 3 and 4, none of the solenoids 25 receive electrical energy. Assuming, however, that the switch 33/I associated with the color zone 8/I is shifted towards the left after the switch 28 was previously closed momentarily, then the solenoid 25/ becomes energized as soon and for as long as contacts 31, 31' are closed by the cam wheel 29. During this time, the eccentric portion of the shaft 29 which is offset through with reference to the cam wheel 29 will shift the rod 14 of the color zone 8/1 via the bifurcated portion 20 of the rod 14 in the direction towards the doctor blade 2, that is upwardly in FIG. 1. Since the solenoid 25/I is energized and hence the associated rod 19 is pulled towards the right in FIG. 1, the projection 15 of the rod 14 is moved into engagement with the teeth of the gear 9 and thereby the cam 3 is turned slightly in clockwise direction. This means, assuming that the starting position is the one shown in FIG. 1, that the bar 5 can recede slightly in downward direction in FIG. 1, permitting the gap G to increase in Width. As soon as the rod 14 reverses its direction of movement, the pair of contacts 31, 31' becomes disengaged and the solenoid 25/I becomes deenergized. This causes the spring 23 to shift the rod 19 towards the left in FIG. 1 and to disengage the projection 15 of the rod 14 from the gear 9. Unless the switch 28 is still closed at this time, the motor 22 will continue to operate until it has imparted another half revolution to the shaft 21, whereupon the contacts 27, 27 become disengaged and thereby interrupt the supply of electric energy to the motor 22.

On the other hand, if the switch 33 of one of the sections I-X is shifted towards the right, for instance the switch 33/I', after the switch 28 has been closed or is still closed, then the solenoid 35/I will receive electrical current and become energized when the contacts 30, 30 engage one another. In this case, the rod 14 will be ready to move downwardly away from the doctor blade 2 in FIG. 1 arid, since it is now made to engage the gear 9, it will turn the same and the cam 7 in counterclockwise direction by a small distance, causing the bar 5 to be shifted towards the doctor blade 2 and the latter to be flexed sufficiently to slightly decrease the width of the gap G.

If during this operation the switch 28 remains closed and the switch 33/ remains engaged in the right-hand position, then the gear 9 is moved in counterclockwise direction during each engagement with the rod 14. Assu ming that this would take place a sufficient number of times, and the highest point of the cam 7 would finally reach the lower end of the bar 5, continued counterclockwise movement of the gear 9 and the cam 7 would then cause the bar to be successively retracted away from the doctor blade 2 as it'would cooperate with ever lower portions of the cam track on the cam 7. In order to avoid this possibility, one of the spaces between the teeth of the gear 9 is filled over approximately one-third of the axial length of the gear 9 with a filler 9' (compare FIGS. 1 and 6) so that upon reaching the highest point of the cam track on the cam 7 the rod 14 cannot engage into the neck-following gap between the teeth of the gear 9. In the arrangement shown in the illustrated embodiment, and referring par- 1 ticularly to FIG. 1 for a showing, it will be seen that the filler 9' is offset by slightly less than 90 with reference to the highest point of the cam track on the cam 7. Because it extends over only approximately one-third of the length of the gap between the two successive teeth in which it is accommodated, the spring 13 can still engage into the remainder of the gap (for which reason it is itself only as wide approximately as one-third of the axial length of the gap) in order to be able to reliably retain .the gear 9 against turning movement.

It remains to be pointed out that the filler 9' could be used as an electrical contact which on being engaged by the projection 15 could be used to trigger an automatic opening of the switch 28.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above.

While the invention has been illustrated and described as embodied in a printing machine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In a printing machine, a combination comprising a printing-ink receptacle having an elongated outlet;

dispensing means, including an elongated flexible doctor blade extending along said outlet and defining a gap of predetermined maximum width which is elongated longitudinally of said doctor blade and through which printing ink is dispensed; and adjusting means for adjusting the width of said gap to thereby vary the amount of printing ink dispensed through the same, said adjusting means comprising a rotatable eccentric shaft extending along said doctor blade, a plurality of pressuretransmitting bars engaging said doctor blade at respective locations which are spaced therealong and each being individually shiftable transversely of said gap to flex the doctor blade and decrease the width of said gap, a plurality of turnable eccentric cams each associated with one of saidbars forshifting the same transversely of said gap, drive means for rotating said eccentricshaft, and motion-transmitting means for transmitting motion from said' shaft to selected ones of said cams so as to effect shifting of the bar which is associated with the. same, so as to increase the width of said gap 'at-someof said locations while at the same time decreasing its width at other locations if required and at the will of an operator. i

2. A combination as defined in claim 1, wherein said adjusting means further comprises a mounting shaft also extending along said doctor blade, a plurality of gears freely turnably mounted on said mounting shaft, each of said cams being fixedly connected with one of said gears for turning with the same, and retaining means for retaining said gears against turning relative to said-shaft in the absence of the transmittal of motion by said motion-transmitting means.

3. In a printing machine, a combination comprising a printing-ink receptacle having an elongated outlet; dispensing means, including an elongated flexible doctor blade extending along said outlet and defining a gap of predetermined maximum width which is elongated longitudinally of said doctor blade and through which printing ink is dispensed; and adjusting means for adjusting the width of said gap to thereby vary the amount of printing ink dispensed through the same, said adjusting means comprising a rotatable eccentric shaft and a mounting shaft each extending along said doctor blade, aplurality of pressure-transmitting barsengaging said doctor blade at respective locations which are spaced therealong and each being individually shiftable transversely of said gap to flex the doctor blade and decrease the width of said gap, a plurality of turnable eccentric cams each associated with one of said bars for shifting the same transversely of said gap drive means for rotating said eccentric shaft, and motiontransmitting means for individuallytransmitting motion from said shaft to respective ones of said cams so as to effect shifting of the bar which is associated with the same, a plurality of gears freely turnably mounted on said mounting shaft, each of said cams being fixedly connected with one of said gears forturning with the same, and retaining means for retaining said gears against turning relative to said shaft in the absence of the transmittal of motion by said motion-transmitting means, said motion-transmitting means comprisinga plurality of first rods having a projection and being movable between a first end position in which said projection engages with and turns one of said gears and a second end position in which it is disengaged from the same, a plurality of second rods each cooperating with one of said first rods and being longitudinally shiftable, biasing means biasing said second rods to a position in which they urge the associated first rods to said second end positions, and solenoid means energizable for urging said second rods to a position in which they urge the associated first rods to said first end positions.

4. A combination as defined in claim 3, wherein said retaining means comprises a plurality of leaf springs each engaging with the teeth of one of said gears.

5. A combination as defined in claim 3, wherein each of said first rods has a bifurcated portion intermediate its opposite ends, and wherein said eccentric shaft extends through and engages said bifurcated portion.

6. A combination as defined in claim 3, wherein said solenoid means comprises a plurality of solenoids, one

for each of said second rods; and wherein said adjusting means further comprises an electric circuit in which all of said solenoids are interposed, and double-pole double-throw switches interposed in said electric circuit in cooperation with each of said solenoids.

7. A combination as defined in claim 6, wherein said adjusting means further comprises a cam member mounted on said rotatable eccentric shaft for rotation with the same, and two make-and-break switches interposed in said circuit and cooperating with said cam member, said cam member being arranged with reference to said make-and-break switches for sequentially closing the same during rotation of said eccentric shaft, 

1. In a printing machine, a combination comprising a printingink receptacle having an elongated outlet; dispensing means, including an elongated flexible doctor blade extending along said outlet and defining a gap of predetermined maximum width which is elongated longitudinally of said doctor blade and through which printing ink is dispensed; and adjusting means for adjusting the width of said gap to thereby vary the amount of printing ink dispensed through the same, said adjusting means comprising a rotatable eccentric shaft extending along said doctor blade, a plurality of pressure-transmitting bars engaging said doctor blade at respective locations which are spaced therealong and each being individually shiftable transversely of said gap to flex the doctor blade and decrease the width of said gap, a plurality of turnable eccentric cams each associated with one of said bars for shifting the same transversely of said gap, drive means for rotating said eccentric shaft, and motion-transmitting means for transmitting motion from said shaft to selected ones of said cams so as to effect shifting of the bar which is associated with the same, so as to increase the width of said gap at some of said locations while at the same time decreasing its width at other locations if required and at the will of an operator.
 2. A combination as defined in claim 1, wherein said adjusting means further comprises a mounting shaft also extending along said doctor blade, a plurality of gears freely turnably mounted on said mounting shaft, each of said cams being fixedly connected with one of said gears for turning with the same, and retaining means for retaining said gears against turning relative to said shaft in the absence of the transmittal of motion by said motion-transmitting means.
 3. In a printing machine, a combination comprising a printing-ink receptacle having an elongated outlet; dispensing means, including an elongated flexible doctor blade extending along said outlet and defining a gap of predetermined maximum width which is elongated longitudinally of said doctor blade and through which printing ink is dispensed; and adjusting means for adjusting the width of said gaP to thereby vary the amount of printing ink dispensed through the same, said adjusting means comprising a rotatable eccentric shaft and a mounting shaft each extending along said doctor blade, a plurality of pressure-transmitting bars engaging said doctor blade at respective locations which are spaced therealong and each being individually shiftable transversely of said gap to flex the doctor blade and decrease the width of said gap, a plurality of turnable eccentric cams each associated with one of said bars for shifting the same transversely of said gap, drive means for rotating said eccentric shaft, and motion-transmitting means for individually transmitting motion from said shaft to respective ones of said cams so as to effect shifting of the bar which is associated with the same, a plurality of gears freely turnably mounted on said mounting shaft, each of said cams being fixedly connected with one of said gears for turning with the same, and retaining means for retaining said gears against turning relative to said shaft in the absence of the transmittal of motion by said motion-transmitting means, said motion-transmitting means comprising a plurality of first rods having a projection and being movable between a first end position in which said projection engages with and turns one of said gears and a second end position in which it is disengaged from the same, a plurality of second rods each cooperating with one of said first rods and being longitudinally shiftable, biasing means biasing said second rods to a position in which they urge the associated first rods to said second end positions, and solenoid means energizable for urging said second rods to a position in which they urge the associated first rods to said first end positions.
 4. A combination as defined in claim 3, wherein said retaining means comprises a plurality of leaf springs each engaging with the teeth of one of said gears.
 5. A combination as defined in claim 3, wherein each of said first rods has a bifurcated portion intermediate its opposite ends, and wherein said eccentric shaft extends through and engages said bifurcated portion.
 6. A combination as defined in claim 3, wherein said solenoid means comprises a plurality of solenoids, one for each of said second rods; and wherein said adjusting means further comprises an electric circuit in which all of said solenoids are interposed, and double-pole double-throw switches interposed in said electric circuit in cooperation with each of said solenoids.
 7. A combination as defined in claim 6, wherein said adjusting means further comprises a cam member mounted on said rotatable eccentric shaft for rotation with the same, and two make-and-break switches interposed in said circuit and cooperating with said cam member, said cam member being arranged with reference to said make-and-break switches for sequentially closing the same during rotation of said eccentric shaft, but for opening both of said switches when said first rods have reached the respective first and second end positions thereof.
 8. A combination as defined in claim 7, said drive means comprising an electric motor; and further comprising a cam wheel mounted on said eccentric shaft and cooperating with a pair of contacts interposed in an actuating circuit of said electric motor and operative for closing said contacts and energizing said circuit only for the duration of one rotation of said eccentric shaft. 